3 -130w 6" KC 121s on one relay

According to the amp draw (32.5) I would think that this is no problem on a 40a relay. KC website says only 2.

 

A 40A relay should be able to manage that power, just make sure the wires are thick enough.

 

my thought also. I might have trash the output wires that come with the 2 light kit for something heavier. I know on AC I would be looking at 8ga. but not sure on DC.

 

I would use three relays for redundancy (unlikely to lose all three lights at once) and longevity (much less strain on the relay contacts).

 

I would recommend a #10 AWG stranded for 40 amps

 

I am thinking 2 relays since there are only 2 outs on the one in the double light kit.

 

As Large mentioned, I'd use 10 ga. for the wire between the power source and the relay. If you run individual wires between the relay and the lights themselves, then you can use whatever wire came with the lights in their kit.

Yota Toy does bring up a good point though. If you're counting on these lights, redundancy could be something to take into consideration. Personally, I just through a couple extra relays in my glove box and if one fails, just swap it out but, if you don't want to have the hassle of fixing your wiring on a dark trail, multiple relays would ensure that at least 1 or 2 of the lights would continue to function.

 

What do you mean '2 outs'? I had assumed you'd all but scrapped the 'kit' wiring since you're wiring 3 lights and had purchased a 40A relay. Make sure your power for the lights isn't going through the switch. Sometimes those 'kits' aren't wired very well.

 

definitely power for lights through relay. I use to do this a lot as a young man but it has been a while. The KC kit has a 40. Sounds like I need to do some research on relays. Right now o am window shopping. In fact I am killing time at dealer while they detail my truck.

 

Oh, ditch the KC relay and pick up a 4 prong automotive relay at your local auto parts store. Just make sure it's a 40A relay as most common ones are only rated for 30. You could quickly splice in a new relay into the KC kit with very little effort.

 

I am trying to figure this out. If the relay has 2 outputs should I power 2 light off 1 and the third off the other? Last time I did this was in the 80s and I had 4 lights on one relay. I am sure I ran 2 off each output.

 

Yep.

Remember that a single pole relay only has one set of contacts. All the power is going through a single contact, the extra output terminal is just an easy way to attach more wiring.

It's worth remembering that whatever wire you put downstream of a fuse should be able to handle what the fuse is rated at.

I have wired two pieces of 14 gauge to a relay output before, and although the wire was rated to handle the amperage of the light it was feeding, it wasn't rated to handle the amperage rating of the fuse. In all likelihood, it would never have been a problem, since the most likely reason for the fuse to blow would be a short to ground, the fuse would go fast. Just something to think about.